1. Field of Invention
The invention relates to a method of locking a positioning mechanism, more particularly, a method of locking a rotating, tilting and positioning vise with cam profile shaped locks.
2. Description of Prior Art
The traditional hand engraving vise which has been in existence since the nineteenth century, consists of a ball base resting in a doughnut type cradle. The top half of the ball is made to pivot on a center axis. On top of this are the vise jaws. When the engraver, jeweler or craftsman desires to hand engrave an arc on an object that is clamped in the jaws, he simply turns the vise with one hand, while the other hand holds the engraving point on the surface of the object that is being engraved. The location of the rotating object being engraved has a direct affect on the degree of difficulty in engraving an arc. The location of the rotating pivot position depends on where the object is clamped in the jaws of the vise. An arc is easiest to engrave when it has its center location closest to the center pivot position of the rotating vise. Engravers and jewelers therefore become accustomed to unclamping, moving and reclamping the object in the vise jaws many times in the course of a project. Unfortunately, clamping and unclamping to position the object in reference to the vise pivoting location can become a problem since the objects engravers and jewelers work on are often delicate and can be damaged if clamped incorrectly. In addition, a lot of time is used unclamping and clamping. Another example of the need to position a working area of an object in the center of a rotating vise is when delicate hand working operations are executed with a microscope. The microscope is centered over the rotating pivot position of the vise. The field of view through the microscope is limited and in order to keep a particular spot in view, the axis of rotation needs to stay in the center of the field of view of the scope, otherwise the area being viewed will swing out of view when the vise is rotated.
Tilting prior art engraving vises utilized a partial sphere for the bottom half of the rotating assembly set in a cradle base made of materials such as rubber and leather. The weight of the vise and the material the cradle is made of determines how much grip is on the sphere to prevent the vise from titling unexpectedly. This method of holding the tilting vise can be unpredictable and the entire vise assembly has been known to fall and tilt unexpectedly.
Disclosed in publication titled GRS POSITIONING VISE by GRS Corporation as well as photographs by applicant of a disassembled GRS Corporation positioning vise is a rotating positioning vise. The vise jaw apparatus on top of this prior art vise is made to slide around for positioning and then lock. The locking mechanism utilizes one spring in earlier models for holding the lock state. Later models used two springs. The one or two springs are connected to a lever. This lever has detent holes in it. There are two steel ball bearings fixed in position in the block that are spaced the same distance as the detent holes in the lever. When the positioning is locked, the holes in the lever do not line up with the holes. In this state the lever is pushing against a friction plate to lock the positioning of the vise. To unlock a user moves the spring loaded lever and the detent holes in the lever then align with the two ball bearings in block. This allows the lever to be lowered and thus loosens the pressure on the friction plate that allows the user to position the vise. The lever requires two hands to overcome the resistance of the springs to unlock. Additionally there is a wear point on a “lock button” described in the GRS Corporation publication. When it is worn, the mechanism will not lock well and requires repair shims. As is true to other prior art, this vise does not have a lock mechanism to lock the tilt.
In short, an improved positioning vise should have a unique and simple method to lock the positioning as well as the tilting movements. The locking mechanisms should be easily and quickly locked and unlocked at will by the user without a lot of resistance effort or needing to use both hands to lock and unlock. The locks should take up any wear themselves and not require repair shims.